INTERFEROMETRIC PHASE AND AMPLITUDE FLUCTUATION MEASUREMENTS OVER A 7KM ATMOSPHERIC PATH
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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A 6328 A laser interferometer of the Michelson type has a one-way path length of 7 km. The fringes are resolved by frequency-modulating the laser sufficiently to sweep over at least one fringe width. By correlation techniques, the resulting fringe intensity pattern is resolved into the true fringe crossing direction and rate and into light amplitude fluctuations. An upper limit of 300 per second is established for the former, the amplitude fluctuations being at a slower rate. With a measured intensity range of up to 50001, it is clear from the data that none of the currently postulated Rayleigh, log normal, or Rice distributions match the amplitude statistics over this full range. A limiting value of standard deviation for the log of the amplitude is 0.85.